Forecasts predict that the next cycle
of sunspots and storms, expected to begin in March 2008, will be moderate
in intensity. But even moderate storms can have a powerful impact, scientists
say, as society has become increasingly dependent on technologies vulnerable
to space weather.

Scientists gathered last Wednesday to announce predictions
for the sun's next cycle of sunspots and storms, slated to begin in March 2008.
Forecasts for upcoming space weather are moderate, but the sun's impact may
still be powerful: With an increasing reliance on technologies based in the
upper atmosphere, the scientists warned, society has become more vulnerable
to the effects of solar storms than ever.

That concern was borne out last December, when two powerful
solar flares disrupted the Global Positioning System (GPS) and other communication
technologies across the planet  at a time when solar activity was expected
to be generally decreasing. Such communication technologies rely on being able
to transmit and receive radio waves across vast distances through the uppermost
part of Earth's atmosphere. The flares injected high-energy particles into the
sun's upper atmosphere and produced radio waves that headed rapidly toward Earth.
The arrival of the burst of radio emissions in December swamped GPS receivers
and created unprecedented levels of "noise" across a broad range of
frequencies. This event marked the first time researchers were able to accurately
record how much effect such bursts had on GPS receivers  and suggests
that even worse may be to come in a few years, when the new solar cycle approaches
its maximum.

The new cycle, labeled "Solar Cycle 24," is already
slightly behind schedule and is now expected to peak around October 2011. This
delay has made predicting the storms' intensity more difficult, Doug Biesecker,
chair of a panel of scientists charged with making the predictions, told reporters
Wednesday at NOAA's annual Space Weather Workshop in Boulder, Colo. The panel,
which consists of 12 members from NASA, NOAA, the International Solar Energy
Society and other agencies, began analyzing a wide range of predictions about
the upcoming sun cycle last October, during the previous cycle's waning period.

During a full solar cycle, the sun's activity increases, peaks
and then decreases, typically over a period of 11 to 12 years. That cycle coincides
with the appearance of dark, lower-temperature areas on the sun's surface where
the magnetic activity is particularly intense. Scientists believe that these
"sunspots" may be the source of solar flares, which are sudden eruptions
of energy that can shower Earth with charged particles and bursts of electromagnetic
radiation.

Earth's protective magnetic field shields much of the planet
from this radiation, but particularly strong flares can make the magnetic field
fluctuate, producing geomagnetic storms that can disrupt communications and
navigation systems. In addition to navigation systems, such flares can have
significant consequences across many sectors, Joe Kunches, head of the Forecast
and Analysis Branch of NOAA's Space Environment Center, told reporters Wednesday.
Satellites in low orbit around Earth are vulnerable to this radiation, which
can cause Earth's upper atmosphere to swell somewhat, interfering with the satellites'
orbits. Solar flares can also endanger astronauts by exposing them to potentially
lethal radiation, and can even increase radiation dangers to pilots and passengers
flying at very high altitudes.

With so much at stake, some key sectors, including airlines,
power grid operators, GPS users and NASA want answers about how strong the next
cycle will be  and sooner rather than later. "Customers are becoming
more demanding than ever before," Kunches said. In terms of the storms'
ultimate socioeconomic impact, "a stronger or weaker solar maximum will
make a big difference in what we can expect," said Dan Baker, a member
of the panel and the director of the Laboratory for Atmospheric and Space Physics
at the University of Colorado at Boulder. NASA relies on space weather data
to help plan its missions years in advance. Airlines, meanwhile, not only need
clear communications but also find it costly to alter flight paths to lower
altitudes to minimize radiation exposure, or to avoid flying closer to the poles,
which are most affected by solar storms. Many sectors also rely heavily on GPS
data, Baker said. "The value of GPS business is in the tens of billions
of dollars, and is expected to rise to three-quarters of a trillion dollars
within the next decade or so."

Scientists, however, are still divided over the predicted
intensity of the next solar cycle. Given in numbers of sunspots per year, the
two competing estimates for maximum activity are 140, peaking in October 2011,
and 90, peaking in August 2012. Although certainly different, both estimates
are relatively moderate, Biesecker said: In comparison, the most active period
in the past 100 years occurred in 1956, when sunspot activity averaged about
200.

No matter how intense the storms are, scientists are keeping
a weather eye out for their potential impact, the panel said. Even during a
solar minimum, the danger is still present, as evidenced by the strong solar
burst last December. That incident, scientists warn, could be just one sign
of things to come.Carolyn Gramling